Roman names consisted of three parts. Name (nomen), family name (nomen gentile) and nickname (cognomen, usually also hereditary).
Interesting is the genesis of the nickname Gaius Julius Caesar. There is a supposition that he comes from an unnatural method of childbirth, known as Caesarean section. Pliny the Elder says that in this way the future dictator was to come into the world. However, against that is the fact that his mother – Aurelia Cotta died only in 54 BCE, while in ancient Rome the law allowed Caesarean section to be carried out only on a dead woman who was pregnant. It is also clear to the fact that these cognomen also bore the ancestors of the dictator. The family of Julius Caesar appears in preserved sources from the third century BCE.
According to Stefan Weinstock, the nickname really took its origin from the way of coming to the world through Caesarean section. In this way, the ancestors of Julius Caesar, were born who lived in the third century BCE or earlier and due to the frequent recurrence of this phenomenon in the family of Iulii, he could have received the nickname of Caesars.
There is also a version saying that the nickname came from the word CAESARIES, which was used to describe thick hair. As Caesar had rather problems with baldness, it may seem that it was his ancestors from the family, they could get such a nickname, because of their “hair”.